flipper

Hey all, I have a stupid ?

I have a couple of rough spots in my accelleration. 1 at about 2500 and another at about 3800. You cant feel them when accelerating hard, just under slow acceleration or deceleration.
I cleaned my MAF and it helped a bit but i can still feel it.
In my area, I only have access to 91 gas.
could gas be an issue?
what octane does my 99 2.5 boxster need?

arenared

Should say on the fuel filler door (and what method, i.e. R+M/2) or in your owner's manual. Don't have a 2.5, but my 3.2 says 93 octane. It runs just fine with 91 though. No rough spots, etc. Haven't heard of this problem before. One possibility could be resonance in the exhaust which occurs in the 2500-3K RPM range mostly. Another long shot is the front engine mount which is known to deteriorate over time/usage.

Macster

to live with 91 octane in CA.

Flat spots not a symptom of using a sub-octane grade of gas. More likely engine deposits. Run a bottle probably two of Techron through engine gas tank, using instructions on bottle label.

I like to do this a tank or 3 before oil change to drain oil that is contaminated with any deposits and fluid from the Techron. It is pretty powerful stuff and Boxster engines do not need any more oil dilution than they get normally.

Going forward buy name brand gas and buy from a busy station cause premium grade of gas can go "off" pretty quickly. A UK car mag did a gas test and found up to a 40% difference in torque output under controlled conditions varying only the gas and using gas of an octane grade recommended by automaker.

Sincerely,

Macster.